The investigators will follow the evidence wherever it leads. If all works out as planned, we could have unambiguous evidence about the biological cause of obesity in the next half a dozen years. The Hormone Hypothesis To understand what makes the hormone hypothesis of obesity so intriguing, it helps to grasp where the energy-balance hypothesis falls short. The idea that obesity is caused by consuming more calories than we expend supposedly stems from the first law of thermodynamics, which merely states that energy can neither be created nor destroyed.
As applied to biology, it means that energy consumed by an organism has to be either converted to a useful form metabolized , excreted or stored. Thus, if we take in more calories than we expend or excrete, the excess has to be stored, which means that we get fatter and heavier. So far, so obvious. But this law tells us nothing about why we take in more calories than we expend, nor does it tell us why the excess gets stored as fat. Specifically, why do fat cells accumulate fat molecules to excess?
This is a biological question, not a physics one. Why are those fat molecules not metabolized instead to generate energy or heat? And why do fat cells take up excessive fat in some areas of the body but not others? Saying that they do so because excess calories are consumed is not a meaningful answer. Answering these questions leads to consideration of the role that hormones—insulin, in particular—play in stimulating fat accumulation in different cells.
Insulin is secreted in response to a type of carbohydrate called glucose. When the amount of glucose rises in the blood—as happens after eating a carbohydrate-rich meal—the pancreas secretes more insulin, which works to keep the blood glucose level from getting dangerously high.
Insulin tells muscle, organ and even fat cells to take up the glucose and use it for fuel. It also tells fat cells to store fat—including fat from the meal—for later use.
As long as insulin levels remain high, fat cells retain fat, and the other cells preferentially burn glucose and not fat for energy. The main dietary sources of glucose are starches, grains and sugars. In the absence of carbohydrates, the liver will synthesize glucose from protein.
The more easily digestible the carbohydrates, the greater and quicker the rise in blood glucose. Fiber and fat in foods slow the process. Thus, a diet rich in refined grains and starches will prompt greater insulin secretion than a diet that is not. Sugars—such as sucrose and high-fructose corn syrup—may play a key role because they also contain significant amounts of a carbohydrate called fructose, which is metabolized mostly by liver cells.
The result, according to the hormone hypothesis, is an ever greater proportion of the day that insulin in the blood is elevated, causing fat to accumulate in fat cells rather than being used to fuel the body.
As little as 10 or 20 calories stored as excess fat each day can lead over decades to obesity. The hormone hypothesis suggests that the only way to prevent this downward spiral from happening, and to reverse it when it does, is to avoid the sugars and carbohydrates that work to raise insulin levels. Appetite, 56 1 , — Liao, Y. Translational Psychiatry, 9, Larrieu, T.
Frontiers in Physiology, 9, Marx, W. Nutritional psychiatry: The present state of the evidence. Proceedings of the Nutrition Society, 76 4 , — This holiday season alone, millions of people will turn to HelpGuide for free mental health guidance and support.
So many people rely on us in their most difficult moments. Can we rely on you? All gifts made before December 31 will be doubled.
Cookie Policy. What are dietary fats? Dietary fat and cholesterol Dietary fat plays a major role in your cholesterol levels.
Conversely, high levels of LDL cholesterol can clog arteries and low HDL can be a marker for increased cardiovascular risk. Good fats vs. These fats can help to: Lower the risk of heart disease and stroke.
Prevent abnormal heart rhythms. Lower triglycerides associated with heart disease and fight inflammation. Lower blood pressure. Prevent atherosclerosis hardening and narrowing of the arteries.
What to do about mercury in fish Despite the health benefits, nearly all seafood contains traces of pollutants, including the toxic metal mercury. What about tropical oils, such as coconut and palm oil? Trans fats are also naturally found in beef fat and dairy fat in small amounts. Trans fats are the worst type of fat for the heart, blood vessels, and rest of the body because they:.
Mozaffarian, D. Micha, and S. Wallace, Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of randomized controlled trials. PLoS Med , Mensink, R. Am J Clin Nutr , Appel, L. JAMA , Department of Agriculture, U. Government Printing Office.
Dietary Guidelines for Americans, , Lichtenstein, A. Circulation , Institute, N. Population, — Being Too Social.
Having a social life is important for maintaining a happy work-life balance. Sitting Too Long. Not Getting Enough Sleep. Not Having Time to Relax. Many people lead busy lives and never have time for themselves. Sadly, not having time to relax could make you feel constantly stressed and gain some fat. Eating From Large Plates and Bowls. The size of your plates and bowls could have a significant impact on your waistline.
Simply switching to smaller tableware may help you eat less food without feeling hungry. Eating in Front of the TV. Drinking Your Calories. Drinking fruit juices, soft drinks and other beverages might be making you gain fat. Not Eating Enough Protein. A lack of protein in your diet might be making you gain fat.
Not Eating Enough Fiber. Taking the Elevator Instead of the Stairs. Not Having Healthy Snacks Handy. Hunger is one of the biggest reasons why people gain weight. Having healthy snacks handy can help combat hunger and curb your cravings for unhealthy foods.
Eating Too Many Healthy Fats. Shopping Without a Grocery List. Shopping without a grocery list might be making you gain fat. Here are a few tips for making a grocery list: Arrange foods by category so that they are easier to locate. This will help save you time and avoid temptation. Drinking Too Many Milky Coffees. Not Eating Enough Fruits and Veggies.
If you find it hard to eat your fruits and veggies, here are a few helpful tips: Add some fruit to your morning oatmeal. Prepare some raw veggie sticks and take them with you to work. Add plenty of chopped vegetables to your soups, stews and lasagnas. Eat vegetable-rich soups and stews as it gets colder outside.
If you find it hard to prepare fresh veggies, try mixing it up with frozen veggies. Using Too Much Dressing. A single serving of salad dressing can contain more calories than your entire salad. Having Irregular Mealtimes. Not Eating Healthy on the Weekend.
The Bottom Line. There are many little things that can make you gain fat. However, you can make lifestyle changes today to account for them. Read this next.
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